Ford's (NYSE:F) Mustang has been a hit with muscle car fanatics over the decades and has appeared in thousands of movies, television shows, and games. For that reason we shouldn't be surprised that Ford will be making a splash for the Mustang's 50th birthday next April -- including being a hero car in a Need for Speed movie. Its birthday also coincides with what is shaping up to be the most important redesign in the Mustang's history.

At a time when Ford is going global with its vehicle lineup, the Mustang doesn't attract consumers outside the U.S. -- forcing a drastic and historic design change. Will the redesign be enough to save the iconic muscle car, or will it be the cause of its ultimate demise?

An artist rendering of a 2015 Ford Mustang. Courtesy of TopSpeed.

Our friends over at TopSpeed just released a rendering of what the 2015 could look like based on some spy photos. Chances are that the designers at Ford will make it more aggressive to attract the younger crowd. This is one of the freshest renderings out there and could be close to what the modern Mustang will look like. It's also possible Ford's designers will go more aggressive on the front end, as pictured here

When the redesigned Mustang is finally revealed -- Ford has kept its new look very secretive -- it will be a night-and-day difference from the retro style we see today. Ford is targeting a different and younger Generation-Y consumer, as well as a fuel-conscious international consumer, and is said to based on the Evos concept vehicle.

Many Mustang owners have expressed their displeasure after viewing the Evos concept, but Ford has been delivering hit after hit with its vehicle designs based on the concept in recent years -- this should be no different. Ford needs the 2015 redesign to hit its mark and revive the slipping Mustang sales.

2013 is projected from sales through May. Information from Automotive News DataCenter.

2015 Mustang specs
Fans of the front-engine, rear-wheel-drive layout have nothing to fear, as that will remain. Die-hard mustang enthusiasts will cheer as they have long awaited to see the Mustang get its independent rear suspension, which the Camaro and Challenger already have.

What's intriguing about the redesigned pony car will be its engine options. Ford's EcoBoost engines have been selling extremely well in other models and according to Car and Driver, a 2.4-liter turbocharged four-cylinder will also be available in the U.S. for the younger consumers who are more interested in fuel efficiency than in raw horsepower. That sound you just heard was Mustang enthusiasts throwing their keyboards out the window at the idea of a Mustang with an EcoBoost engine. 

Fortunately for those who just lost their keyboards, they'll be happy to know the standard 3.7 liter V-6 and 5.0 liter V-8 will of course still be available for us power-hungry consumers. For the Mustang to gain global popularity and rebound from years of declining sales, as well it should, the EcoBoost will be absolutely key to selling in Europe and China. 

Bottom line
You saw the sales decline the Mustang has suffered through, and this redesign will be make-or-break for the iconic muscle car's future. General Motors' (NYSE:GM) Chevy Camaro has outsold the Mustang the past three years and is on pace to continue that trend in 2013. Last year the Mustang sold just under 83,000 models, which was only the eighth best model in Ford's lineup. Its sales haven't broken 100,000 vehicles since 2007, and the trend isn't going to reverse unless the new design retains die-hard fans and attracts younger consumers.

Its next-generation Mustang is an even bigger deal for Ford and its investors, because it represents more to the company than just 83,000 in sales. It's a halo vehicle, an iconic car for Ford's brand image and advertisement in the media. When consumers think of getting the most muscle for their buck, the Mustang comes to mind immediately.

The Mustang driver in me cringes at the idea of what the redesigned muscle car would look like to sell overseas, as Ford is planning. As an investor, I cringe at the idea that Ford could flop with its design and alienate its die-hard fans in the U.S., as well as swinging and missing with global ambitions. The risk and reward are huge, and if Ford can make this new style a hit here in the U.S. as well as in Europe and China, we could be witnessing the rebirth of the Mustang into one of Ford's most popular and profitable vehicles.

One thing is for sure: The Mustang's 50th birthday is going to be one heck of a show. I expect the new design to be unveiled then, and I can't wait to officially see it. Ford designers, consumers, and investors are all hoping it's a smash hit -- and with Ford's track record recently, I bet it will be.

Fool contributor Daniel Miller owns shares of Ford and General Motors. The Motley Fool recommends Ford and General Motors and owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.